Power devices are electronic components designed to be tolerant of the high currents and voltages that are present in power applications such as motion controlled air bag deployment and automotive fuel injector drivers. The power lateral double-diffused metal-oxide-semiconductor (LDMOS) field-effect-transistor (FET) device, referred to herein as a power LDMOS device, is becoming increasingly popular for such power applications. As power technologies develop, power applications require smaller and smaller power devices with a high breakdown voltage.
Many applications for power LDMOS devices require the inclusion of a series connected reverse diode on certain output nodes in order to realize voltage blocking capability in both positive and negative directions. When the application cannot tolerate the LDMOS body diode, such as when there is a regular output with no reverse path from the output to the input, a discrete diode in series with the LDMOS or two back-to-back LDMOS structures are used to achieve high breakdown voltage in both directions. There exists a problem with device mismatch when multiple LDMOS devices are required or an LDMOS-diode structure is required. In these types of devices a certain percentage of mismatch is expected. Insulated gate bipolar transistors (IGBTs) provide for an alternative structure.
IGBTs are designed for power applications and combine metal-oxide-semiconductor (MOS) gate control and a bipolar current flow mechanism. An IGBT incorporates features of both a metal-oxide-semiconductor field effect transistor (MOSFET) and a bipolar junction transistor (BJT). IGBTs have higher current density than MOSFETs and faster switching characteristics than BJTs. IGBTs are the primary choice today for high-power (>10 kW), low to medium frequency (up to 30 kHz) applications.
IGBT devices feature high current/high voltage operation and high input impedance at the same time. Replacing power LDMOS multi-structures with an insulated gate bipolar transistor (IGBT) provides significant savings in the required device area. That is, IGBT devices are significantly smaller than an LDMOS-diode structure or a LDMOS—LDMOS structure because the on-resistance in an IGBT is lower.
In addition, conventional LDMOS devices suffer from minority carrier current in to the substrate which can harm the surrounding devices. IGBT device structures are less susceptible to such substrate injection. IGBTs typically, do not have the same reverse recovery time associated with a standard LDMOS body diode.
Accordingly, it is desirable to provide a high voltage IGBT structure for silicon bulk based (non silicon-on-insulator (SOI)) power integrated circuits (ICs). Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.